Chemical reaction eats up CO2 to produce energy ... and other useful stuff

Transmission electron microscopy image of carbon nitride created by the reaction of carbon dioxide and Li3N

While there are plenty of ways to make carbon-based products from CO2, these methods usually require a lot of energy because the CO2 molecules are so stable. If the energy comes from the burning of fossil fuels, then the net result will be more CO2 entering the atmosphere. Now a material scientist at Michigan Technological University has discovered a chemical reaction that not only soaks up CO2, but also produces useful chemicals along with significant amounts of energy.

Professor Yun Hang Hu and his research team developed a heat-releasing reaction between CO2 and lithium nitride (Li3N) - a compound that is the only stable alkali metal nitride and is made by reacting lithium with nitrogen at room temperature. Reacting lithium nitride with carbon dioxide resulted in amorphous carbon nitride (C3N4), a semiconductor, and lithium cyanamide (Li2CN2), a precursor to fertilizers.

“The reaction converts CO2 to a solid material,” said Hu. “That would be good even if it weren’t useful, but it is.”

In terms of energy release, when Hu’s team added CO2 to less than a gram of Li3N at 330° C (626° F), the surrounding temperature shot up almost immediately to 1,000° C (1,832° F) – which they point out is roughly the temperature of lava flowing from a volcano.